Answer:
1).A mixture having a uniform composition where the components can't be seen separately and all components are in the same state best describes a solution. In chemistry, a solution is a homogeneous mixture composed of two or more substances.
(1 cal/g °C) x (4000 g) x (45 - 25)°C = 80000 cal = 80 kcal. So the answer is 80 kcal .
Here, Initial momentum = mu = 6*2 = 12 Kg m/s
Final momentum = mv = 6*4 = 24 Kg m/s
In short, Your Answer would be Option C
Hope this helps!